Journal of Geophysical Research: Biogeosciences最新文献

{"title":"Tracking Long-Term Trends in Sockeye Salmon (Oncorhynchus nerka) Population Dynamics Using Sterol and Stanol Biomarkers in Lake Sediments","authors":"D. Dagodzo,&nbsp;D. C. Eickmeyer,&nbsp;L. E. Kimpe,&nbsp;D. T. Selbie,&nbsp;J. P. Smol,&nbsp;J. M. Blais","doi":"10.1029/2025JG008903","DOIUrl":"10.1029/2025JG008903","url":null,"abstract":"<p>We analyzed biomarkers, including sterols, stanols, and δ¹⁵N, in sediment cores from lakes with well-documented sockeye salmon return histories. Our goal was to improve estimates of past changes in salmon escapement, that is, the population that return to their freshwater nursery lakes, inferred using sediment biogeochemical markers. Cholesterol, the predominant sterol in adult sockeye salmon muscle tissue, displayed a strong positive relationship with escapement (<i>R</i>² = 0.8, <i>p</i> = 0.001, and <i>F</i>_1,8 = 28.3). Sediment concentrations of the plant-derived sitosterol and algal-derived fucosterol, absent in salmon muscle tissue also related positively with salmon escapement, suggesting that salmon-derived nutrients from decomposing fish promote the production of these lipids by primary producers in the lakes. We developed a novel salmon sterol index (SSI_a) from values in surface sediments of the nine Alaskan lakes [(cholesterol + coprostanone + epicoprostanol + desmosterol)/(cholesterol + coprostanone + epicoprostanol + desmosterol + fucosterol + sitosterol + stigmastanol)] that was strongly related with salmon return density (pseudo <i>R</i>² = 0.86 and RMSE = 0.071). This index also tracked historical sockeye escapement patterns and δ¹⁵N values in ²¹⁰Pb-dated lake sediment cores from Frazer, Karluk, Red, and Kinaskan lakes that span more than a century of salmon population history, suggesting that the index has potential as a proxy for tracking historical salmon populations, particularly when used in combination with independent biomarkers of salmon-derived nutrient inputs. SSI_a and the other salmon sterol indices we developed show promise for improving and extending long-term sockeye salmon population estimates using lake sediment records, which will help inform salmon conservation and management efforts.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG008903","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Neural Network-Based Estimate of the Seasonal to Inter-Annual Variability of the Lake Superior Carbon Cycle","authors":"Daniel E. Sandborn,&nbsp;Elizabeth C. Minor,&nbsp;Jay A. Austin","doi":"10.1029/2024JG008610","DOIUrl":"10.1029/2024JG008610","url":null,"abstract":"&lt;p&gt;Lake Superior emits and absorbs CO&lt;sub&gt;2&lt;/sub&gt; with significant seasonal and interannual variability, which complicates efforts to constrain its carbon cycle. While it regains atmospheric CO&lt;sub&gt;2&lt;/sub&gt; equilibrium on sub-annual scales, resulting in a sustained rise in observed &lt;i&gt;p&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt; over the last two decades, significant gaps in observation have prevented examination of variability in its carbon cycle on smaller temporal or spatial scales. We developed a reconstruction of daily mean Lake Superior surface water &lt;i&gt;p&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt; and CO&lt;sub&gt;2&lt;/sub&gt; lake-air flux with a spatial resolution of 0.02° &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${times} $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; 0.02° in order to infer trends and drivers of carbon cycling in Lake Superior on seasonal to interannual scales. A feed-forward neural network was trained and tested on underway &lt;i&gt;p&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt; measurements spanning ice-free seasons of 2019–2023, yielding a spatially-comprehensive product describing inorganic carbon dynamics over a five-year period. Lake Superior alternated between net annual CO&lt;sub&gt;2&lt;/sub&gt; influx and efflux, with values ranging from &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;0.30&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.06&lt;/mn&gt;\u0000 &lt;mspace&gt;&lt;/mspace&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mtext&gt;Tg&lt;/mtext&gt;\u0000 &lt;mspace&gt;&lt;/mspace&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;mspace&gt;&lt;/mspace&gt;\u0000 &lt;mtext&gt;yr&lt;/mtext&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${-}0.30pm 0.06,{text{Tg},mathrm{C},text{yr}}^{-1}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; (influx) to &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;0.06&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.06&lt;/mn&gt;\u0000 &lt;mspace&gt;&lt;/mspace&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mtext&gt;Tg&lt;/mtext&gt;\u0000 &lt;mspace&gt;&lt;/mspace&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;mspace&gt;&lt;/mspace&gt;\u0000 &lt;mtext&gt;yr&lt;/mtext&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $0.06pm 0.06,{text{Tg},mathrm{C},text{yr}}^{-1}$&lt;/an","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JG008610","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Year-Round δ13C-CH4 Reveals Seasonal Transition in Methane-Related Processes in a Boreal Mire","authors":"Xuefei Li,&nbsp;Janne Rinne,&nbsp;Eeva-Stiina Tuittila,&nbsp;Timo Vesala","doi":"10.1029/2025JG008922","DOIUrl":"10.1029/2025JG008922","url":null,"abstract":"<p>While boreal mires are known to be a significant natural source of methane (CH₄), the seasonality of the related processes and their controls are still poorly understood. Here we aim to characterize CH₄ production, oxidation and transport, and their drivers in a boreal mire using year-round continuous measurements of stable carbon isotope composition (δ¹³C-CH₄) in dissolved and emitted CH₄. We found reversed vertical profiles of δ¹³C-CH₄ in the summer (higher values at surface) and in the winter (higher values at bottom). The ¹³C enriched emitted CH₄, as compared to pore water CH₄, indicated methane oxidation at the peat-snow interface by sphagnum mosses in the winter. The observed hysteretic δ¹³C-CH₄ - pCH₄ relation indicated the importance of substrate availability for methane production in addition to soil temperature, and their time-lagged seasonal cycles. Our data also demonstrated the dominance of plant-mediated transport in the summer, the dominance of diffusion through peat and moss matrix (with associated microbial methane oxidation) in the winter and a transition in the spring and autumn. In general, the measured δ¹³C values of emitted CH₄ at this and other northern mires are considerably lower than the values used in atmospheric inversion models. Our comprehensive data set provided invaluable insight into wetland δ¹³C-CH₄, the dynamic interplay of multiple processes related to CH₄ emission in boreal mires, especially in the rarely studied winter, spring, and autumn, the incorporation of which into Earth System Models will allow more accurate prediction of wetland responses to ongoing climate change.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG008922","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shaping DOM Signatures in East Antarctic Lakes: Penguins, Mosses, Meltwater, and Processing Mechanisms","authors":"Liza K. McDonough,&nbsp;Amy D. Holt,&nbsp;Eliza Hamilton,&nbsp;Krystal Randall,&nbsp;Krystyna M. Saunders,&nbsp;Sharon A. Robinson,&nbsp;Robert G. M. Spencer,&nbsp;Amy M. McKenna,&nbsp;Lauren Linnenlucke,&nbsp;Karina T. Meredith","doi":"10.1029/2025JG008931","DOIUrl":"10.1029/2025JG008931","url":null,"abstract":"<p>Rapid environmental changes in Antarctica highlight the need to understand the role of its lakes as potential carbon cycling hotspots. Dissolved organic matter (DOM) in these lakes drives biogeochemical processes, yet its sources and transformations remain poorly characterized. We investigated DOM molecular composition in five lakes from the Windmill Islands, East Antarctica, combining molecular-level data with biogeochemical data to infer DOM sources. Our findings revealed that DOM formulas in the lakes match many formulas identified in penguin guano (PG). Lakes with high amounts of formulas matching guano-derived DOM were enriched in nitrogen-containing formulas (e.g., CHON, <i>p</i> &lt; 0.05) and bioactive metals (Cu, Ni, and Mn; <i>p</i> &lt; 0.05) linked to penguin diet. Fresh snowmelt also contributed DOM, with inputs increasing with decreasing lake elevation (<i>p</i> &lt; 0.01). Additionally, many lake DOM formulas matched secondary organic aerosols or photodegradation by-products identified in Antarctic snow, characterized by elevated aliphatics (<i>p</i> &lt; 0.01). Moss-derived DOM further contributed to the pool, resulting in relatively higher O/C ratios and aromaticity (<i>p</i> &lt; 0.05). A comparison of mass differences between molecular formulas suggested that abiotic transformations largely governed lake DOM processing. As environmental conditions continue to shift, altering moss cover and penguin populations, the composition and transformation pathways of lake DOM may change, with ramifications for carbon cycling. These results highlight a surprising diversity and complexity in DOM sources and cycling dynamics across a small number of Antarctic lakes and underscore the need for further research to fully understand regional carbon dynamics in this rapidly changing environment.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG008931","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pioneering Evidence of the Dynamics of Water Vapor and CO2 Fluxes in Sahara Desert Soils","authors":"N. Bekin,&nbsp;D. S. Ashilenje,&nbsp;A. Chehbouni,&nbsp;L. Bouchaou,&nbsp;D. Kool,&nbsp;N. Agam","doi":"10.1029/2025JG009193","DOIUrl":"10.1029/2025JG009193","url":null,"abstract":"<p>Soil CO₂ flux (<i>F</i>_<i>c</i>) is a major component of the global carbon balance. It is often overlooked in arid regions as low soil moisture restricts microbial and root respiration. Studies in the last decades challenge this paradigm, reporting an anomalous diurnal cycle of <i>F</i>_<i>c</i> in arid regions. This diurnal cycle is thought to be initiated by geochemical reactions in the soil. This hypothesis is controversial since <i>F</i>_<i>c</i> occurs even during the driest soil conditions when no apparent water is available to dissolve the soil CO₂. We used a static chamber system, as well as profiles of temperature and relative humidity sensors accompanied by meteorological measurements, to provide the first evidence of water vapor and CO₂ fluxes in dry soils of the Sahara Desert, Morocco. We show that water vapor advected inland from the Atlantic Ocean is diffused into the dry soil. Using soil-specific vapor sorption isotherms, we show that the soil water content increased nightly by 0.7%–1% as water vapor was adsorbed to soil particles. The water vapor flux was significantly correlated to <i>F</i>_<i>c</i> (<i>r</i>² = 0.76, <i>p</i>-value &lt; 0.001), supporting the hypothesis that water vapor adsorption (WVA) provides the water source to initiate nocturnal soil CO₂ uptake. The quality of the correlation and the magnitude of <i>F</i>_<i>c</i> were affected by the soil's specific surface area, salinity, and reactive CaCO₃ content. These findings suggest that WVA initiates chemical reactions that consume soil CO₂ even in the driest environments.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009193","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Distinct Accumulations of Microbial Necromass Carbon in Mangrove, Salt Marsh, and Bare Flat Wetlands","authors":"Jine Wei,&nbsp;Fenfen Zhang,&nbsp;Yanling Zheng,&nbsp;Xiaofei Li,&nbsp;Hongpo Dong,&nbsp;Xia Liang,&nbsp;Guoyu Yin,&nbsp;Changwei Lü,&nbsp;Min Liu,&nbsp;Lijun Hou","doi":"10.1029/2025JG009059","DOIUrl":"10.1029/2025JG009059","url":null,"abstract":"<p>As a key component of stable soil organic matter, microbial necromass carbon (MNC) serves as a pivotal contributor to long-term carbon sequestration in coastal blue carbon ecosystems. Despite its recognized importance, the ecosystem-specific characteristics and accumulation mechanisms of MNC remain poorly understood across various coastal wetlands. In the present study, surface soils contained higher MNC contents than subsurface soils across mangroves, salt marshes, and bare flats. Additionally, distinct accumulations of MNC were found across the three types of wetlands. Mangrove wetlands exhibited a significantly higher MNC contents, especially bacterial necromass carbon (BNC) contents, compared with salt marsh and bare flat wetlands. Nitrogen availability, especially total nitrogen (TN), microbial biomass nitrogen (MBN), and the ratio of microbial biomass carbon to MBN, emerged as key drivers of necromass formation, emphasizing the importance of nutrient regulation. Furthermore, BNC accumulation in mangrove soils may be improved by iron-mediated stabilization. Interestingly, BNC exhibited the opposite trend from fungal necromass carbon (FNC), which contributed less to soil organic carbon (SOC) in mangroves than in salt marshes and bare flats. The overall proportions of MNC in the SOC pool are similar across all wetland types despite these disparate contributions, most likely as a result of a dilution effect resulting from the accumulation of refractory, plant-derived organic carbon in mangroves. Elucidating these dynamics is crucial for advancing our understanding of wetland carbon restoration of these ecosystems to enhance their carbon sequestration potential.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vegetation Productivity in India Is Modulated by Climate Teleconnections From the Pacific Ocean","authors":"Nivedita Dubey,&nbsp;Vittal Hari,&nbsp;Ana Bastos,&nbsp;Subimal Ghosh","doi":"10.1029/2024JG008682","DOIUrl":"10.1029/2024JG008682","url":null,"abstract":"<p>Vegetation productivity in India varies at intraseasonal to interannual time scales, influenced by meteorological factors sensitive to large-scale climate teleconnections. While the impact of global climate variability on Indian monsoon and its extremes is well known, their effects on Indian vegetation productivity are relatively less understood. This study addresses this gap by decomposing dominant modes of spatio-temporal variability of gross primary productivity (GPP) over India and examining their dependence on climate teleconnections. We found that El-Niño Southern Oscillation (ENSO) and Pacific Meridional Mode (PMM) significantly impact GPP, especially in western and southern peninsular India during the monsoon and post-monsoon seasons (correlation coefficient = ∼0.5). However, there is an east-west asymmetry in the PMM-GPP correlation. The western region and southern peninsula are negatively correlated, while northeast India positively correlates with PMM. Using wavelet decomposition, we show that more than half of temporal variability in the GPP comprises low-frequency components. These low-frequency signals primarily drive the relationship between GPP and climate teleconnections. Next, we identify the dominant spatial modes of low-frequency signals of GPP. We tested the predictability of the principal components of GPP using teleconnections and hydrometeorological variables. While most of the predictive skill of GPP comes from its past (memory up to 5 months, <i>R</i>² score of up to 0.5), adding teleconnection indices as predictors improves the prediction skill at lead times (with an increase of 30%–50% in <i>R</i>² values, and up to 10%–15% reduction in RMSE). Our results underscore the utility of using hydrometeorological and distant climate teleconnection in GPP prediction for longer lead times.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transition in Biomineralization Mechanisms From Early to Late Stages of Deep-Sea Bamboo Corals: Insights From fs-LA-ICP-TOFMS Elemental Imaging","authors":"Miaohong He,&nbsp;Xuna Yin,&nbsp;Xuefei Chen,&nbsp;Kaiwen Ta,&nbsp;Xiaotong Peng,&nbsp;Hengchao Xu,&nbsp;Hong Yan,&nbsp;Xuefeng Wang,&nbsp;Pengli He,&nbsp;Declan Morrissey,&nbsp;Wenfeng Deng,&nbsp;Gangjian Wei","doi":"10.1029/2024JG008463","DOIUrl":"10.1029/2024JG008463","url":null,"abstract":"<p>The elemental compositions of deep-sea corals are invaluable proxies in high-resolution reconstructions of deep-sea paleo-oceanographic conditions, but the incorporation of minor and trace elements into their skeletons and associated biomineralization are poorly understood. In this study, multielement (Cd, P, Ba, K, S, Co, Mn, Fe, Sr, Na, and Mg) and fluorescence imaging of skeletal cross-sections of a subapical branch and middle-basal trunk of a deep-sea bamboo coral, <i>Jasonisis</i> sp. (collected from the seafloor in front of the Mariana arc (11.95355°N, 141.47446°E) at a depth of 1,385.9 m in October 2019) were undertaken using femtosecond laser ablation-inductively coupled plasma time-of-flight mass spectrometry and laser scanning confocal microscopy, respectively. The spatial associations of minor and trace elements and their organic compositions, and associated growth patterns (cyclic rings) of early- (the subapical branch and the near-core region of the middle and basal trunk) and late-stage (the middle-basal trunk excluding near-core regions) coral skeletons were determined simultaneously. The consistent distribution patterns of most elements and the presence of distinct rings correspond to growth patterns associated with nutrient-like elements such as Cd, P, and Ba and organic components within the late skeleton. This likely suggest a significant role of nutrients in the biomineralization process during the late stage. The distinct elemental patterns, exhibiting positive correlation among specific elements (e.g., P, S, Mn, Co, and Cd) and negative correlations with others (e.g., Na and Mg), along with the lower organic content observed in the early skeleton, suggest a unique mineralization mechanism during the initial growth stage, with kinetic processes playing a dominant role. Therefore, combined multielement and organic composition mapping of different parts of coral skeletons provides comprehensive insight into coral growth and the incorporation of trace elements.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical Versus Climatic Controls on Soil Organic Carbon","authors":"Shaun A. Watmough,&nbsp;Chetwynd Osborne,&nbsp;M. Catherine Eimers,&nbsp;Colin J. Whitfield","doi":"10.1029/2025JG009050","DOIUrl":"10.1029/2025JG009050","url":null,"abstract":"<p>Soil texture and climate are considered the major controls on soil organic carbon (SOC) storage globally, and model simulations suggest that cooler regions of the planet will be more sensitive to SOC losses caused by climate warming. To investigate this pattern, we measured SOC and geochemical properties in surface (0–10 cm) mineral soil at 198 forested sites across the Boreal Plains, Boreal Shield, and Taiga Shield Ecozones in central Canada, where mean annual air temperature (MAT) ranged from −6.0 to +0.7°C. Across the five ecoregions, SOC was strongly related to soil organic matter (SOM) with SOC:SOM ratio of 0.47. Despite the substantial temperature gradient, we found that SOC was only weakly correlated with temperature, precipitation, and net primary productivity (NPP). Instead, SOC was strongly related (<i>r</i> &gt; 0.7) to soil geochemical properties with SOC increasing in finer textured soils that had higher concentrations of aluminum (Al) and iron (Fe) and lower silica (Si) content. To extend the climate and soil geochemistry gradient, we expanded the analysis to include soils from temperate forests in the Mixedwood Plains Ecozone of southeastern Canada as well as published data from natural shrublands and grassland sites spanning the Southern Hemisphere and found that the strong correlations between SOC, Al + Fe, and Si persisted. These data suggest that soil texture and geochemical properties provide protection to SOC, and relationships with geochemistry must be incorporated in Earth System Models to improve spatial prediction of SOC stocks and their sensitivity to climate change.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009050","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145058002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metalimnetic CO2 and N2O Maxima in a Deep Hydropower Reservoir: Implications for Degassing and Downstream Emissions","authors":"Xingcheng Yan,&nbsp;Hao Sun,&nbsp;Qiuwen Chen,&nbsp;Jianyun Zhang,&nbsp;Tao Feng,&nbsp;Xudong Zhou,&nbsp;Ruxia Qiao","doi":"10.1029/2025JG009122","DOIUrl":"10.1029/2025JG009122","url":null,"abstract":"<p>The vertical profiles of dissolved greenhouse gas (GHG) concentrations provide pivotal information about their dynamics in reservoir water columns; however, our knowledge remains constrained. This study quantified the vertical distributions of GHG concentrations and their diffusive fluxes in a major tributary of a large and deep reservoir on the Lancang River, China. The metalimnetic oxygen minima phenomenon was observed, corresponding to the peak values of carbon dioxide (CO₂) and nitrous oxide (N₂O) concentrations along the water column. The concentrations of CO₂ and N₂O were significantly correlated to the saturation of dissolved oxygen, suggesting that the aerobic respiration and nitrification processes play crucial roles in driving their vertical patterns. The relative water column stability significantly correlated with the chemical stratification index of physiochemical water variables as well as CO₂ and N₂O concentrations, indicating the importance of water stratification in regulating both the vertical patterns of water variables and the concentrations of CO₂ and N₂O. Moreover, the sediment within the transition zone between fluvial and lacustrine phases may be a hotspot for GHG production, which was supported by the high GHG concentrations in the deep water. Overall, the GHG diffusive fluxes from the studied area were much lower than global reservoir averages. Although our results show that vertical GHG concentrations do not necessarily correlate with surface concentrations, the large variations in the vertical distributions of GHG concentrations still emphasize the importance of selecting the reservoir outlet depth to manage GHG emissions through degassing and downstream pathways.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"130 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145037730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}